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The evidence that oxygen is the only effective treatment in viral bronchiolitis continues to mount. The largest double blind, randomised, placebo controlled trial to date of nebulised adrenaline (epinephrine) showed no improvement in duration of hospital stay/time until ready for discharge with adrenaline compared with placebo. Indeed, in those with more severe bronchiolitis, adrenaline was associated with an increase in the duration of hospital stay. There was no improvement in oxygenation or clinical score in the group receiving adrenaline. The best predictor of severity of bronchiolitis and duration of stay in hospital was oxygen saturation in room air at admission. Interestingly, oxygen saturation at admission was also a good predictor of severity in acute asthma.
Previous studies of the role of adrenaline in bronchiolitis have shown improved respiratory mechanics and clinical severity scores but the methodology has been flawed with too few patients, inclusion of older infants with previous wheezing episodes, and lack of clinically important outcomes (for example, duration of hospitalisation or need for intensive care/mechanical ventilation). Bronchodilators have not been shown to be effective in bronchiolitis although a trial of their use is common, especially in older infants with a personal or family history of atopy. Wainright’s paper suggests that adrenaline is not effective in this subgroup, although the study was not sufficiently powered to answer this question.
It would appear that, for the moment at least, supplemental oxygen and supportive care remain the only effective treatment for viral bronchiolitis.